This invention relates generally to the field of pressurized fluid systems and more particularly, but not by way of limitation, to a pressure relief valve which establishes a bypass path for a pressurized fluid in the event of an overpressure condition, the relief valve configured to accommodate different internal orifice sizes which can be readily installed during field use.
Pressurized fluid systems are provided with pressure relief capabilities to prevent injury to personnel and damage to equipment in the event of an overpressure condition. An overpressure valve assembly, sometimes also referred to as a main valve or a pilot valve, can be used to establish a bypass path for the pressurized fluid.
In such a valve assembly, inlet fluid bears against a piston assembly which is biased in a closed position against a valve seat. When the pressure of the fluid generates sufficient force upon the piston assembly to overcome the bias force, the piston assembly moves to an open position away from the valve seat and the fluid flows to an outlet port.
The setpoint at which a valve assembly opens is selected based on the requirements of the system. As those skilled in the art will appreciate, a number of factors are taken into account in configuring a particular valve assembly to open at a particular pressure setpoint. These factors can include the operational pressure range for the fluid, the respective diameters of the inlet and outlet ports, the cross-sectional surface area of the piston assembly impacted by the inlet flow, the distance the piston assembly moves between the opened and closed positions, and the diameter of a restriction orifice upstream from the piston assembly used to regulate the volumetric flow through the valve once the piston assembly is opened.
It is sometimes desirable to reconfigure an existing valve assembly to have a different internal orifice size. Because the foregoing factors can be interdependent, changing over to a new orifice size can require replacement of a number of other internal components within the valve assembly as well. This can be cost and labor intensive. In some circumstances, it may be deemed more desirable to simply procure and install a new, replacement valve assembly configured from the factory with the new orifice size rather than reconfiguring an existing valve assembly in the field.
There is therefore a continued need for improvements in the art to address these and other limitations of the prior art, and it is to such improvements that the present invention is directed.
In a first aspect, presently preferred embodiments of the present invention are generally directed to a method and apparatus for configuring a pressure relief valve to have a desired internal orifice size.
The apparatus preferably comprises a valve seat assembly for use in a pressure relief valve having a moveable piston assembly which is biased against the valve seat assembly in a normally closed position and which moves away from the valve seat assembly when a pressure of an inlet pressurized fluid reaches a predetermined threshold.
The valve seat assembly preferably includes a substantially cup-shaped seat body comprising an annular wall and an inwardly directed, annular seat flange, the annular wall having opposing first and second ends, an inner surface and an outer surface. The annular seat flange extends from the first end of the annular wall to abut the piston assembly when the pressure relief valve is in the closed position.
The valve seat assembly further comprises an annular wall with opposing first and second ends, an outer surface and an inner orifice of a first diameter. The first insert slidingly engages the seat body so that the outer surface of the first insert abuts the inner surface of the seat body. In this way, the inner orifice meters a flow rate of fluid through the valve seat assembly.
The seat body is further configured to accommodate a replacement, second insert comprising an annular wall with opposing first and second ends, an outer surface and an inner orifice of a second diameter less than the first diameter. In this way, the inner orifice of the second insert meters a second flow rate of fluid through the valve seat assembly less than that provided by the inner orifice of the first insert.
Preferably, the valve seat assembly further comprises a resilient seal ring configured to be supported by the first end of the first insert and disposed between the insert and the annular seat flange of the seat body. The seal ring preferably includes an annular contact surface configured to abuttingly receive the piston assembly and establish a fluidic seal when the pressure relief valve is in the closed position, wherein the resilient seal ring is further configured to be supported by the first end of the second insert.
The seal ring further preferably comprises an annular ring of rigid material, and an annular ring of resilient material surrounding and attached to the annular ring of rigid material. The annular ring of rigid material is preferably formed of steel and the annular ring of resilient material is preferably formed of rubber. The stiffener ring resists relaxation of the seal ring over time.
The method of reconfiguring the valve seat assembly preferably comprises steps of removing the first insert from the seat body, and inserting the second insert into the seat body so that the outer surface of the second insert abuts the inner surface of the seat body.
In another aspect, presently preferred embodiments of the present invention are generally directed to a resilient seal ring for use in establishing a fluidic seal in a pressure relief valve having a moveable piston assembly which is biased against a valve seat assembly which supports the resilient seal ring when the valve is in a closed position.
The resilient seal ring preferably comprises an annular stiffener ring of rigid material, and an annular ring of resilient material surrounding and attached to the annular ring of rigid material, wherein the piston assembly compresses an annular contact surface defined by the resilient material when the valve is in the closed position.
Preferably, the rigid material comprises steel and the resilient material comprises rubber. The annular stiffener ring of rigid material preferably comprises an inner wall surface which defines an aperture through which pressurized fluid flows when the piston assembly is moved away from the valve seat assembly by a pressure of said fluid. Moreover, the annular stiffener ring of rigid material further preferably comprises a resilient material attachment surface which depends from the inner wall surface, with the annular ring of resilient material abutting the resilient material attachment surface.